A simple drawing with value shades in two colors: you need just a pencil, a rubber, and two colored pencils. First, you draw a tree with its branches with a pencil. You create many areas of negative space ready to be filled with shades of two colors. Second, we choose two colored pencils in gradation (like orange and red, or light blue and dark blue).
To create the colored shades you begin at one end of the area pressing the colored pencil and decreasing the pressure towards the center of the area. With the other color, you begin at the opposite end, lightening the color towards the center. In this way you overlap the lighter colors in the center, creating the shades.